Our small communities tend to be tough, resilient and hospitable places, especially towards the furthest points of the country. Natural disasters bring their people together, and they absorb such tragedies because of linked interests and shared needs. The shift happens when a murder occurs, then damage is done to the fabric, and more is torn than just the flesh of the victim.

A few weeks ago, my colleague Lorna Martin wrote an article marking the 10th anniversary of the killing of Shamsudden Mahmood on Orkney. Even for those not from the islands, the thought of a masked man walking into an Indian restaurant in Kirkwall, shooting the waiter and then walking out again, was almost incomprehensible. For Orcadians, who hadn't dealt with a murder for 25 years, it was incomprehensible.

The first theories reflected the disbelief. Mahmood was from Bangladesh, so imaginations were immediately aflutter. It was a gangland killing. There were drugs involved. It was a family feud. He had vast gambling debts. Most of all, it was a sin visited on the islands by a rough, foreign humanity, the killer disappearing down an alley, never to be seen again.

As time went on and the case remained unsolved, the story, and the theories, found long-term homes in the darker recesses of memory.

They didn't go away, though. While I don't want to be kitsch, we do have a national sense of hospitality, and the fact that a visitor was murdered in Scotland resonated. Yet, until Lorna wrote her piece, I hadn't realised that Michael Ross, a local man, had been named in court as the main suspect. I didn't know that the current head of CID at Northern Constabulary believes this was a racist murder.

This silence terrifies me. The CID officer made his revelation to Donald John MacDonald, the producer of a Grampian television series, Unsolved - Getting Away With Murder. The programme on Mahmood, shown in January, was, MacDonald said, 'the most disturbing, but the one that got the least reaction from the public'.

It turns out that Mahmood wasn't a drug-snorting, dice-rolling, gangbanger. It turns out that he was a gentle and much-loved member of a normal family. He was saving up to go home and study law. 'There was no reason to kill him,' said his brother, Shafiuddin.

There is a new theory about what happened. The police found the case of the 9mm bullet that killed Mahmood. Pc Eddie Ross, president of the local gun club, was asked to check all the guns on the island. He omitted to mention his sealed box of 9mm bullets, or produce a second box he was known to have bought. Ross was sent to jail for four years for wilful neglect and violation of duty. Michael, his son, was named as prime suspect at his trial, although he had only been 15 at the time.

Apart from the many tragedies in this story, it is easy to ask questions of the assumptions made in the wake of the killing. It seems to have a resonance of the Stephen Lawrence case, in that Mahmood was demonised while the truth cause was probably banal, ugly racism. Yet the police have been intent in pursuing this crime. In its aftermath, they sealed off the airport and the ferry terminals, and they questioned nearly every adult in Kirkwall. They also appear to have shown no favour when it turned out one of their own had withheld information.

The police were probably no more and no less racist than the rest of us; we were all so quick to believe it had to be someone foreign to commit such a crime. And while the police have tried to address their mistake, it seems we, the public, remain at fault. If the reaction to Macdonald's documentary is anything to go by, it appears we don't really care. We cause no fuss. We fail to push for it to be solved.

Mahmood's family - he was the baby in a family of 11 children - would be saints if they didn't now believe Scotland to be a cesspool of racism. 'When we were told the murder was racist, we all felt terrible,' Shafiuddin said. 'We thought Britain was a racially tolerant society. We feel that if [the killing] had been investigated more vigorously, the criminal would have been brought to justice by now.' You can't blame them. Their brother was a guest in our country and he was shot in the head.

According to the fiscal, there is insufficient circumstantial evidence to proceed. In Orkney, there is a sense that people are hoping the memory will fade. Yet there are those in the police who would like the case be taken to a jury anyway, believing the evidence equal, if not better, to that which convicted Elgin's Nat Fraser of killing his estranged wife, despite the her body not being found.

Once again, I don't want to be too kitsch, but we are a people rooted in our history and traditions. It's horrible that there are people in another country who believe we will let their citizens be killed, and not at least attempt to convict the man we think responsible. Until we make that attempt, we cannot forget this case. It should ring in our conscience with all the power and disgrace of any injustice. After all, we still harp on about the hanging of James of the Glen, and the killings in Glen Coe.